Fluid blast circuit breaker



FLUID BLAST lCIRCUIT. BREAKER Filed NOV. 5, 1.938-

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@as pressure source Ihvelnto: Davdjc. Farnce, bg WAM/y 'r His Attorney.

vPatented Aug. 19, 1941 2,253,197 FLUID BLAST CIRCUIT BREAKER David' C. Prince, Swarthmore, Pa.,`assignor to General Electric Company, a corporation of New York Application November 3, 1938, Serial No. 238,631

3 Claims.

My invention relates to fluid blast circuit breakers, and has for its principal object the provision of an improved gas blast circuit breaker wherein a source of stored blast energy, such as spring energy for example, is utilized in combination with an independent source of pressure for effecting arc interruption under all operating conditions. v

The commercial use of gas blast circuit breakers has been retarded to a certain extent by the possibility of failure of the gas pressure supply when it is desired to interrupta heavy overload or short circuit current. In such cases opening of the breaker contacts in the absence of an adequate gas blast might result in destruction of the breaker as well as further damage wherein an indoor station is involved.

In accordance with my invention such a hazard is greatly minimized by storing a predetermined amount of blast energy, such as by a spring charging operation, and by utilizing this energy upon failure of the main pressure source both to open the breaker contacts and to supplyl an effective gas blast for arc interruption. Therefore, in the case of failure of the main pressure source, the breaker automatically opens and the arc is interrupted by a gas blast in the usual manner. With this arrangement the stored blast energy is also utilized for normal current interruptions so that the main pressure source can be most. economically used.

My invention will bemore fully set forth in the following description referring to the accompanying drawingkand the features of novelty which characterize :gy-invention will be pointed out with particularit'yinthe claims annexed to and forming a part of this specification.

Referring to the drawing the single figure thereof is an elevational view, partly in section and partly diagrammatically shown, of a gas blast circuit breaker embodying the present invention. Y

The circuit breaker, as shown, is of the transverse or cross blast type and comprises a pair of relatively movable contacts I and 2 mounted within an insulating casing 3 which forms a blast passage 4 through which gas under pressure is f breakers, more particularly to gas blast circuit' directed transversely of the arc path between the contacts.

The gas blast exhausts through a diverging arc chute 5 having insulating arc splitters 8 for purposes well 4known in the art. The contact I is fixed within the casing 3 at one side of the blast passage and is connected to one of the breaker terminals I. The coacting contact 2 with its extension is guided for reciprocal movement in the opposite side of the casing 3 and is likewise suitably connected to theA opposite breaker terminal 2'. The contact 2 is normally biased by a spring l toward open circuit position, the spring being seated between a piston 8 and its cylinder 9. The contacts may also be provided with short diverging arc runners Ia and 2a respectively.

The piston 8 is connected to and movable with the contact 2 so that in combination with the spring 1 it has a double function in both closing the breaker when gas under pressure is admitted to the cylinder head at I0 and also creating a gas blast during the opening operation. During thev circuit closing operation, the spring l is placed under tension and -is held in charged position by gas pressure within the cylinder 9. The piston and cylinder therefore serve in effect at this stage as an expansible reservoir for blast energy. f

When this energy is released the breaker is opened and the piston 8 delivers a gas blast from the cylinder 8 to the arc passage 4 by way of the conduit II. A blast control valve I2, normally biased by a spring I3 to close the blast passage 4, as illustrated, is opened to admit the blast to the contacts in a manner presently described.

The main source of gas pressure, such as a tank and compressor for example, for operating the circuit breaker is generally indicated at I4 and is connected through 4a breaker control valve I5, to the blast valve housing I6. The valve housing I6 is provided with a bypass Il communicating with the conduit II through a nonreturn valve I8. As illustrated, the valve I8 is closed except when the pressure in the bypass exceeds that in the conduit I I.

The operation of the circuit breaker is as follows: Assuming that the breaker is in the open circuit position illustrated and that it is desired to close the same, the valve I5 is actuated in any suitablemanner, as by an operating solenoid I8 and a remote control switch 20 to connect the main pressure source at Il with the valve housing I6. This is accomplished in the present instance by reciprocal movement of a plunger valve comprising a pair of cylindrical valve members I5a and I5b. The valves I5a and I5b are interconnected by a reduced valve stem I5c arranged so that as the plunger valve is operated. by solenoid I8 against the bias of a spring 2l, it uncovers the valve port at 22. In this operation the valve member I5b also closes the exhaust port at 25.

Gas under pressure is accordingly delivered tothe main valve housing I6 from where it is directed through the bypass I'I to the cylinder 8 to close the breaker. The contact 2 remains closed as long as'gas pressure is maintained at the piston 8; It will ybe noted that when the valve I5 is in the open position, the valve portions I5a and Ilib function as pistons which are spring at I3 is eiective to maintain the blast passage I closed, as illustrated. When the valve lib is closed as shown, it should tightly seal that end of the valve casing, as otherwise the gas pressure from Ilmight force the valve open.. In case of gas leakage, however, a pin hole vent can be provided at the end of the casing which lib abuts to overcome this difficulty.

The opening operation of the circuit breaker, as in response to an overload or short circuit on the line, can be accomplished by the usual current transformer 23, in combination with a relay 24, for energizing a second valve operating solenoid 25. The valve I5 is thereupon operated to the closed position against the gas pressure. In this position the valve housing I6 is directly vented as shown to atmosphere at 26. The pressure differential resulting from release of pressure at the lower side of the valve I2 causes depression of the valve against the bias of spring I3 and opening of the blast passage I. The charged spring 1 is thereupon released to cause opening movement of the contact 2 and piston B and return of the stored blast energy through the conduit II to the blast passage 4 where the resulting blast interrupts the arc. It should be noted that the full blast pressure is instantly available even before movement of the piston 8 is initiated. The piston, however, serves to susy tain the blast. In the type of air blast breaker `original arc gap has lengthened to the extent ordinarily required, the arc may be extinguished at the splitters. By reason of the higher pressure and the correspondingly high dielectric strength of the gas blast at the original gap, restriking of the arc is less probable after the arc has been interrupted at a current zero. This is parti-cularly important in high voltage breakers where restr'iking pf the arc due to recovery voltage may be encountered.

During the arc ,interrupting blast, which coincides with the separation of the contacts, the non-return valve Il is closed and the entire blast to release the blast energy stored in the cylinder 9.

It should be understoodthat my invention is not limited to specific details of construction and arrangement thereof herein illustrated, and that changes and modifications may occur to one skilled in the art without departing from the spirit of my invention.

What I claim as new and desire to secure by Letters Patent of the United States is:

i 1. A gas blast circuit breaker comprising separable contacts. means forming a blast passage to said contacts, means for storing blast energy comprising a spring biased piston operatively connected to said contacts, a main source of gas pressure, a valve for controlling communication between said'source and piston for closing said breaker and storing said blast energy, said valve being normally maintained in open position by gas pressure from said source, means biasing said valve toward closed position upon decrease of said source pressure, a mechanically separate blast control valve independent of said first-named valve for controlling communication between said piston and said blast passage, means for maintaining said blastl valve normally closed, and electromagnetic means associated with said first valve for releasing pressure at one side of l said blast control valve when said iirst valve is closed for causing opening of said blast valve thereby releasing a. gas blast through said passage under influence of said stored blast energy.

2. A gas blast circuit breaker comprising separable contacts, means forming a blast passage to said contacts, means for storing blast energy comprising a spring biased piston operatively connected to said contacts, a main source of gas is directed past the valve I2 and through the arc path. The breaker reclosing operation is accomplished in the manner above described.

Assuming now that the breaker is in the normally closed circuit position, and that the main gas pressure source fails, the stressed valve spring 2|, when the gas pressure drops suiciently, will close the valve I5 to cause tripping of the breaker and arc interruption in the manner above described. Even in the event that the valve I5 fails to function properly, the drop in pressure within the valve housing IS would accomplish the same result, since the unbalanced pressure at the valve I2 would cause opening of the same v open said last mentioned pressure, a valve for controlling communication between said source and piston for closing said breaker and storing said blast energy, said valve being maintained in open position by gas pressure from said source, means biasing said valve toward closed position upon decrease of said source pressure, a blast control valve for controlling communication between said piston and said blast passage, spring means for maintaining said blast valve' normally closed, means associated with said first valve for releasing pressure at one side of said blast control valve when said ilrst valve is closed for causing opening of said blast .valve thereby releasing a gas blastv through said first valve, and spring means for biasing said ilrstvalve against saidsource pressure toward the aforesaid pressure releasing position whereby failure or predetermined decrease of said source pressure results in operation of said iirst valve by said spring.

3. A gas blast circuit breaker comprising separable contacts, means forming a blast passage to said contacts, means for storing blast energy including a gas reservoir, a blast valve ior controlling admission of gas from said reservoir to said blast passage, a main source of gas pressure, and a second mechanically separate valve means independent of said blast valve for controlling communication between said source and said reservoir to permit storage of blast energy in 'said reservoir, means forming a gas passage communicating with said blast valve, said second valve means .also being separately operable to gas passage to cause opening of said blast valve.

DAVID C. PRINCE. 

